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Subject: Re: [DCHAS-L] Benchtop Methylene Chloride Use in Undergraduate OChem labs
Date: Tuesday, November 18, 2014 2:02:10 PM
Author: Ralph Stuart <rstuartcih**At_Symbol_Here**me.com> 		Next by Date:
Subject: [DCHAS-L] Chemical Fume Hood Evaluation Form
Date: Tue, 18 Nov 2014 19:48:25 +0000
Author: Wayne Wood

From: Alan Hall <ahalltoxic**At_Symbol_Here**GMAIL.COM>
Subject: Re: [DCHAS-L] Benchtop Methylene Chloride Use in Undergraduate OChem labs
Date: Tue, 18 Nov 2014 12:37:35 -0700
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: CAHFAP+72qSfkc7kCrqz402wFaK=Uebikt5JpTYcbvyorJ-F9WQ**At_Symbol_Here**mail.gmail.com
In-Reply-To <314476593.1937145.1416286464125.JavaMail.zimbra**At_Symbol_Here**comcast.net>


All,

Good to see all the responses.

Medical Toxicology Note: If there is acute poisoning incident, older medical literature might indicate that there could be a significant carbon monoxide (CO) components due to hepatic metabolism of Methylene Chloride to CO. While this does occur (and with methylene bromide and methylene iodide as well), the levels of CO found are usually less than those seen in smokers and the main acute toxicity is the general anesthethic effects of the parted component, which can be fatal by causing respiratory depression and cardio-pulmonary arrest from hypoxemia. It was actually still being used as an obstetric anesthesia agent in Germany into the 1950s.

Methylene chloride can also cause skin injury through a defatting process.

My 0.002 cents worth.

Alan
Alan H. Hall, M.D.
Medical Toxicologist
Azle and Springtown, TX

On Mon, Nov 17, 2014 at 9:54 PM, <drsamples**At_Symbol_Here**comcast.net> wrote:
Dear All,

I have a question for anyone involved in undergraduate Organic Chemistry labs.

Methylene chloride is listed as a recognized carcinogen in California, and it is a B2 probable human carcinogen. As you all know, it is a volatile liquid commonly used in undergraduate Organic Chemistry labs as the organic solvent in liquid-liquid extractions using a separatory funnel. As many OChem labs lack adequate fume hoods, many colleges do these extractions at the bench, and so are venting methylene chloride in the general laboratory. Generally, these are not microscale extractions, but are regular lab scale with a 250 or 500 mL sep funnel.

It is a volatile probable human carcinogen and thus I believe that it should be handled in the fume hood and the extraction should also be done in a fume hood. Do you agree or disagree? If you agree, have you been successful in changing how your department handles methylene chloride in undergrad labs, and if so, how did you successfully argue your case to handle it in fume hoods?

SIncerely,

Marjorie Samples
Chemistry Professor
Los Rios Community College District
California


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